Fetal Magnetic Resonance Imaging Scans Research Articles

Frequency of MRI Low Signal Intensity in the Buccal Fat of Fetuses and Speculation as to What It May Reflect.

We aimed to characterize the fetal buccal fat pad (BFP) on magnetic resonance imaging (MRI) to determine the frequency and types of sequences on which the BFP demonstrates low signal intensity and determine any possible correlation with timing of the MRI during fetal development. A retrospective review of all fetal MR studies was performed, and a pediatric radiologist blinded to the referring and final fetal diagnosis as well as outcome evaluated the included cases. A positive buccal fat pad sign (BFS) was recorded as present if a round, symmetric, and bilateral area was seen in the submalar region of the face with the following signal characteristics: T1 hyperintensity, low signal on echo planar imaging (EPI), low signal on true fast imaging with steady-state free precession (TRUFI), and with restriction on diffusion-weighted imaging (DWI). A total of one hundred sixty-seven (167) fetal MRI studies: one hundred fourteen (114) body (68%) and fifty-three (53) neuro (32%) scans were reviewed during the study period. The BFS was most commonly seen on EPI (63%) and TRUFI (49%) sequences. Substantial agreement between TRUFI and EPI (κ = 0.68; p < 0.01); moderate agreement between TRUFI and T1 (κ = 0.53; p < 0.01) as well as T1 and EPI (κ = 0.53; p < 0.01), and fair agreement between EPI and Diffusion (κ = 0.28; p < 0.01) was observed. The median gestational age (GA) was 24 weeks (IQR 22-30 weeks). The fetuses with a positive BFS were significantly older (mean GA of 27 weeks or higher) than those without, for each sequence. The focal low signal in the fetal buccal fat pad, termed the fetal BFS, is a commonly encountered normal finding in the majority of fetal MRI scans on TRUFI and EPI sequences. This finding may be related to the presence and development of brown adipose tissue in the buccal fat pad resulting in T2* effects, but further studies are needed in order to confirm this. Further work can incorporate any of the sensitive sequences demonstrating low signal in brown adipose tissue to map its distribution and development in the fetus and beyond.

The influence of antenatal imaging on prenatal bonding in uncomplicated pregnancies: a mixed methods analysis

BackgroundPrenatal bonding describes the emotional connection expectant parents form to their unborn child. Research acknowledges the association between antenatal imaging and enhanced bonding, but the influencing factors are not well understood, particularly for fathers or when using advanced techniques like fetal magnetic resonance imaging (MRI). This study aimed to identify variables which may predict increased bonding after imaging.MethodsFirst-time expectant parents (mothers = 58, fathers = 18) completed a two-part questionnaire (QualtricsXM™) about their expectations and experiences of ultrasound (n = 64) or fetal MRI (n = 12) scans in uncomplicated pregnancies. A modified version of the Prenatal Attachment Inventory (PAI) was used to measure bonding. Qualitative data were collected through open-ended questions. Multivariate linear regression models were used to identify significant parent and imaging predictors for bonding. Qualitative content analysis of free-text responses was conducted to further understand the predictors’ influences.ResultsBonding scores were significantly increased after imaging for mothers and fathers (p < 0.05). MRI-parents reported significantly higher bonding than ultrasound-parents (p = 0.02). In the first regression model of parent factors (adjusted R2 = 0.17, F = 2.88, p < 0.01), employment status (β = -0.38, p < 0.05) was a significant predictor for bonding post-imaging. The second model of imaging factors (adjusted R2 = 0.19, F = 3.85, p < 0.01) showed imaging modality (β = -0.53), imaging experience (β = 0.42) and parental excitement after the scan (β = 0.29) were significantly (p < 0.05) associated with increased bonding. Seventeen coded themes were generated from the qualitative content analysis, describing how scans offered reassurance about fetal wellbeing and the opportunity to connect with the baby through quality interactions with imaging professionals. A positive scan experience helped parents to feel excited about parenthood. Fetal MRI was considered a superior modality to ultrasound.ConclusionsAntenatal imaging provides reassurance of fetal development which affirms parents’ emotional investment in the pregnancy and supports the growing connection. Imaging professionals are uniquely positioned to provide parent-centred experiences which may enhance parental excitement and facilitate bonding.

Characterizing microstructural development in the fetal brain using diffusion MRI from 23 to 36weeks of gestation.

We utilized motion-corrected diffusion tensor imaging (DTI) to evaluate microstructural changes in healthy fetal brains during the late second and third trimesters. Data were derived from fetal magnetic resonance imaging scans conducted as part of a prospective study spanning from 2013 March to 2019 May. The study included 44 fetuses between the gestational ages (GAs) of 23 and 36weeks. We reconstructed fetal brain DTI using a motion-tracked slice-to-volume registration framework. Images were segmented into 14 regions of interest (ROIs) through label propagation using a fetal DTI atlas, with expert refinement. Statistical analysis involved assessing changes in fractional anisotropy (FA) and mean diffusivity (MD) throughout gestation using mixed-effects models, and identifying points of change in trajectory for ROIs with nonlinear trends. Results showed significant GA-related changes in FA and MD in all ROIs except in the thalamus' FA and corpus callosum's MD. Hemispheric asymmetries were found in the FA of the periventricular white matter (pvWM), intermediate zone, and subplate and in the MD of the ganglionic eminence and pvWM. This study provides valuable insight into the normal patterns of development of MD and FA in the fetal brain. These changes are closely linked with cytoarchitectonic changes and display indications of early functional specialization.

Reproducibility of 2D versus 3D radiomics for quantitative assessment of fetal lung development: a retrospective fetal MRI study

PurposeTo investigate the reproducibility of radiomics features extracted from two-dimensional regions of interest (2D ROIs) versus whole lung (3D) ROIs in repeated in-vivo fetal magnetic resonance imaging (MRI) acquisitions.MethodsThirty fetal MRI scans including two axial T2-weighted acquisitions of the lungs were analysed. 2D (lung at the level of the carina) and 3D (whole lung) ROIs were manually segmented using ITK-Snap. Ninety-five radiomics features were extracted from 2 and 3D ROIs in initial and repeat acquisitions using Pyradiomics. Radiomics feature intra-class correlation coefficients (ICC) were calculated between 2 and 3D ROIs in the initial acquisition, and between 2 and 3D ROIs in repeated acquisitions, respectively.ResultsMRI data of 11 (36.7%) female and 19 (63.3%) male fetuses acquired at a median 25 + 0 gestational weeks plus days (GW) (interquartile range [IQR] 23 + 4 − 27 + 0 GW) were assessed. Median radiomics feature ICC between 2 and 3D ROIs in the initial MRI acquisition was 0.733 (IQR 0.313–0.814, range 0.018–0.970). ICCs between radiomics features extracted using 3D ROIs in initial and repeat acquisitions (median 0.908 [IQR 0.824–0.929, range 0.335–0.996]) were significantly higher compared to 2D ROIs (0.771 [0.699–0.835, 0.048–0.965]) (p < 0.001).ConclusionFetal MRI radiomics features extracted from 3D whole lung segmentation masks showed significantly higher reproducibility across repeat acquisitions compared to 2D ROIs. Therefore, fetal MRI whole lung radiomics features are robust diagnostic and potentially prognostic tools in the image-based in-vivo quantitative assessment of lung development.

Short- and Long-Term Outcomes of Prenatally Diagnosed Dandy-Walker Malformation, Vermian Hypoplasia, and Blake Pouch Cyst.

Dandy-Walker continuum, which includes Dandy-Walker malformation, vermian hypoplasia, and Blake pouch cyst, is among the most commonly diagnosed posterior fossa malformation by fetal magnetic resonance imaging (MRI). The objective of our retrospective study was to evaluate fetal and postnatal MRI scan and clinical outcomes. Seventy-two patients were identified; 40 patients had postnatal imaging and follow-up (7 Dandy-Walker malformation, 26 vermian hypoplasia, and 7 Blake pouch cyst). Although all patients with Dandy-Walker malformation required ventriculoperitoneal shunts and 66% were intubated at birth, none required tracheostomy tube and 2 of 5 surviving children had no neurologic deficits. Vermian hypoplasia was strongly associated with genetic conditions and cardiac malformations; odds of not ambulating normally were 12 times greater if a syndrome or injury was present. Echocardiogram and genetic screening are recommended with vermian hypoplasia. There is a risk for epilepsy in both Dandy-Walker malformation and vermian hypoplasia. Blake pouch cyst can be complicated by hydrocephalus, but outcome is favorable.

Fetal Micrognathia and Airway Establishment on Placental Support.

* Abbreviations: ETT: : endotracheal tube EXIT: : ex utero intrapartum treatment POPS: : procedure on placental support A 36-year-old gravida 3, para 2-0-0-2 pregnant woman was referred to our fetal care center at 20 5/7 weeks’ gestation because of fetal micrognathia, lagging femur length, and a single umbilical artery. Her pertinent medical and surgical histories included asthma and a prior cesarean section. The pregnancy was the product of in vitro fertilization. Preimplantation genetic screening demonstrated an embryo with a normal karyotype. Her medications included fluticasone propionate/salmeterol, montelukast, lansoprazole, and prenatal vitamins. Family history revealed 2 paternal female first cousins once removed with Smith-Lemli-Opitz syndrome and seizure disorder related to sodium channelopathy. Her standard prenatal screening results were unremarkable. Evaluation at our fetal care center included the following: Figure 1. Fetal magnetic resonance imaging scan obtained at 20 weeks’ gestation. A. The abnormal facial profile with severe micrognathia. B. Facial profile; white arrow indicates glossoptosis. The conglomeration of these fetal findings is consistent with a diagnosis of Pierre Robin sequence. Pierre Robin sequence occurs …

Visualisation of fetal meconium on post-mortem magnetic resonance imaging scans: a retrospective observational study.

BackgroundLess invasive techniques for fetal post-mortems are increasingly used to correlate with parental wishes. With the use of post-mortem magnetic resonance imaging (MRI), normal appearance of the organs must be established.PurposeTo investigate the after death appearance of the fetal meconium throughout gestation using the hyperintense appearance of meconium on T1 weighted MRI.Material and MethodsThis was a retrospective study that took place in a tertiary referral centre radiology department. Sixty-two fetal body post-mortem MRI scans (January 2014 to May 2018) between 12 and 41 weeks gestation were reviewed. Signal intensity of meconium at the rectum, sigmoid colon, splenic flexure and hepatic flexure was evaluated and correlated with gestational age. Interrater reliability was calculated.ResultsMeconium did not consistently have high signal intensity on T1 scans and was not always obvious. Rectal meconium had the highest intensity, and the more proximal the bowel the lower the intensity. The meconium had higher intensity at earlier gestations. Interrater reliability for rectal meconium gradings was excellent.ConclusionThis study provides the first published primary research on the appearance of fetal meconium on post-mortem MRI. Overall, results were variable and suggest an alteration of bowel contents after death, but further investigation is needed to effectively inform practice.

Deep Predictive Motion Tracking in Magnetic Resonance Imaging: Application to Fetal Imaging.

Fetal magnetic resonance imaging (MRI) is challenged by uncontrollable, large, and irregular fetal movements. It is, therefore, performed through visual monitoring of fetal motion and repeated acquisitions to ensure diagnostic-quality images are acquired. Nevertheless, visual monitoring of fetal motion based on displayed slices, and navigation at the level of stacks-of-slices is inefficient. The current process is highly operator-dependent, increases scanner usage and cost, and significantly increases the length of fetal MRI scans which makes them hard to tolerate for pregnant women. To help build automatic MRI motion tracking and navigation systems to overcome the limitations of the current process and improve fetal imaging, we have developed a new real-time image-based motion tracking method based on deep learning that learns to predict fetal motion directly from acquired images. Our method is based on a recurrent neural network, composed of spatial and temporal encoder-decoders, that infers motion parameters from anatomical features extracted from sequences of acquired slices. We compared our trained network on held-out test sets (including data with different characteristics, e.g. different fetuses scanned at different ages, and motion trajectories recorded from volunteer subjects) with networks designed for estimation as well as methods adopted to make predictions. The results show that our method outperformed alternative techniques, and achieved real-time performance with average errors of 3.5 and 8 degrees for the estimation and prediction tasks, respectively. Our real-time deep predictive motion tracking technique can be used to assess fetal movements, to guide slice acquisitions, and to build navigation systems for fetal MRI.

Umbilical vein infusion of prostaglandin I2 increases ductus venosus shunting of oxygen-rich blood but does not increase cerebral oxygen delivery in the fetal sheep.

The ductus venosus (DV) is a dynamic fetal shunt that allows substrate-rich blood from the umbilical vein to bypass the hepatic circulation. In vitro studies suggest a direct role of prostaglandin I2 (PGI2 ) in the regulation of DV tone; however, the extent of this regulation has not been determined in utero. 4D flow and T2 oximetry magnetic resonance imaging can be combined to determine blood flow and oxygen delivery within the fetal circulation. PGI2 increases DV shunting of substrate-rich blood but this does not increase cerebral oxygen delivery. During fetal development, the maintenance of adequate oxygen and nutrient supply to vital organs is regulated through specialized fetal shunts. One of these shunts, the ductus venosus (DV), allows oxygen-rich blood to preferentially stream from the placenta toward the heart and brain. Herein, we combine magnetic resonance imaging (MRI) techniques that measure blood flow (4D flow) and oxygen saturation (T2 oximetry) in the fetal circuit to determine whether umbilical vein infusion of prostaglandin I2 (PGI2 , regulator of DV tone ex utero) directly dilates the DV and thus increases the preferential streaming of oxygen-rich blood toward the brain. At 114-115 days gestational age (dGA; term = 150 days), fetal sheep (n = 6) underwent surgery to implant vascular catheters in the fetal femoral artery, femoral vein, amniotic cavity and umbilical vein. Fetal MRI scans were performed at 119-124 dGA. 4D flow and T2 oximetry were performed to measure blood flow and oxygen saturation across the fetal circulation in both a basal state and whilst the fetus was receiving a continuous infusion of PGI2 . The proportion of oxygenated blood that passed through the DV from the umbilical vein was increased by PGI2 . Cerebral oxygen delivery was unchanged in the PGI2 state. This may be a result of decreased flow from the right to left side of the heart as blood flow through the foramen ovale was decreased by PGI2 . We have shown that although PGI2 acts on the DV to increase the proportion of oxygen-rich blood that bypasses the liver, this does not increase cerebral oxygen delivery in the fetal sheep.

Prenatal brain MRI samples for development of automatic segmentation, target-recognition, and machine-learning algorithms to detect anatomical structures

In this data note, we present a sorted pool of fetal magnetic resonance imaging (MRI) specimens. These were selected for a project seeking to further develop computer vision software called MaZda, which was originally created for magnetic resonance (MR) image analysis. A link to download the samples is provided in the manuscript herein. This data descriptor further explains how and why these fetal MRI samples were selected. Firstly, thousands of cross-sectional images obtained from fetal MRI scans were processed and sorted semi-manually with other software. We did so because a built-in “samplesort” (sorting algorithm) is missing in MaZda version 5. Additionally, the software is unfortunately lacking effective and efficient algorithms to allow automatic identification and segmentation of anatomical structures in fetal MRI samples. Hence, the final sorting steps were carried out manually via time-consuming methods (i.e., human visual detection and classifications by the gestational age of pregnancy and the rotational plane of the MR scanner). Thus, the latter correlates with the anatomical plane of the mother, rather than the hypothetical plane used to transect the fetus. In brief, we collated these fetal MRI samples in an effort to facilitate future research and discovery, especially to aid the improvement of MaZda.

Neurodevelopmental outcome of isolated ventriculomegaly: a prospective cohort study.

Data regarding the neurodevelopmental outcome of children diagnosed in utero with isolated ventriculomegaly (IVM) are limited and principally founded on ultrasound-based studies. Here, we endeavored to assess the outcome of such cases in a large-scale, magnetic resonance imaging (MRI)-based study. We conducted a study on 133 cases of IVM with a documented fetal brain MRI scan. Children were assessed at ages 18 to 36months by using the Vineland Adaptive Behavior Scales (VABS). Vineland Adaptive Behavior Scales scores were within normal range. There was no significant difference between VABS score in symmetric versus asymmetric IVM (101.7 vs. 101.6, respectively; p=0.94), and the VABS score of mild IVM was comparable with that of moderate IVM (101.8 vs. 101; p=0.8). Only five cases (3.8%) were found to have an abnormal score (<85). There was no significant difference in the rate of abnormal scores between mild and moderate IVM (2.8% vs. 8.3%, respectively; p=0.22). In cases of isolated ventriculomegaly, a normal neurodevelopmental outcome is to be expected; moreover, the outcome does not appear to be affected by the severity or asymmetry of the ventriculomegaly. Thus, following a meticulous workup, patients can be given reassuring counseling regarding the child's prognosis. © 2017 John Wiley & Sons, Ltd.

Prenatal brain MRI samples for development of automatic segmentation, target- recognition and machine-learning algorithms to detect anatomical structures

In this data note, we present a sorted pool of fetal magnetic resonance imaging (MRI) specimens, selected for a project seeking to further develop a computer-vision software called MaZda, originally created for magnetic resonance (MR) image analysis. A link to download the samples is provided in the manuscript herein. This data descriptor further explains how and why these fetal MRI samples were selected. Firstly, thousands of cross-sectional images obtained from fetal MRI scans were processed and sorted semi-manually with other software. We did so because a built-in “samplesort” (sorting algorithm) is missing in MaZda version 5. Additionally, the software is unfortunately lacking effective and efficient algorithms to allow automatic identification and segmentation of anatomical structures in fetal MRI samples. Hence, the finals sorting steps were carried out manually via time-consuming methods — i.e. human- visual detection and classifications by the gestational age of pregnancy and the rotational plane of the MR scanner. Thus the latter correlates with the anatomical plane of the mother, rather than the hypothetical plane used to transect the fetus. In brief, we collated these fetal MRI samples in an effort to facilitate future research and discovery, especially to aid the improvement of MaZda.

Role of magnetic resonance imaging in the prenatal diagnosis of gastrointestinal fetal anomalies.

This study was done to evaluate the role of fetal magnetic resonance imaging (MRI) in the study of gastrointestinal malformations in comparison to prenatal ultrasound (US). A prospective (2010-2012) study of 38 fetal MRI scans was performed on 38 fetuses between 24 and 38 weeks of gestation. All the fetuses had a US diagnosis of gastrointestinal anomalies. T2-weighted HASTE, T1-weighted fast gradient echo, TrueFISP and diffusion-weighted images of the fetal abdomen were obtained on a 1.5-Tesla magnet. All fetal MRI diagnoses were compared with postnatal US findings, autopsy or surgical reports. Fetal MRI was able to confirm the sonographic findings in nine of 38 fetuses (23.7%), to provide additional information in 23 of 38 fetuses (60.6%), to exclude the US diagnosis in five cases (5.2%) and to change it in two cases (5.2%). It was not able to characterize a case of gastric duplication and a case of abdominal cystic lymphangioma (5.2%). Fetal MRI can be used as a complementary imaging modality to US in prenatal evaluation of gastrointestinal anomalies and can be considered a valuable tool not only for confirming or excluding but also for providing additional information to fetal ultrasonographic findings.

Complementary role of magnetic resonance imaging after ultrasound examination in assessing fetal renal agenesis: a case report.

IntroductionUltrasonography is used routinely during pregnancy to screen and detect fetal abnormalities. However, there are some conditions like anhydramnios (a prevalent state in renal agenesis) or maternal obesity that may limit the diagnostic accuracy of ultrasonography. Magnetic resonance imaging has proven to be useful when ultrasound alone is insufficient to make a correct diagnosis.Case presentationWe present the case of a 22-year-old Caucasian woman who was admitted to our unit at the 26th week of gestation for a detailed anatomy scan. Anhydramnios and failure to visualize the kidneys, bladder and renal vessels were confirmed with the use of sonography in our department. Since the lack of amniotic fluid limited the acoustic window for fetal ultrasonography, a magnetic resonance imaging scan was requested to confirm suspected renal agenesis. A fetal magnetic resonance imaging scan was performed and confirmed the suspected diagnosis. A baby boy was born by breech vaginal delivery after spontaneous onset of labor at the 34th week of gestation. The boy weighed 1690g, with Apgar scores of 6 and 4 at two and five minutes respectively, and died one hour after delivery. The diagnosis of bilateral renal agenesis was confirmed on autopsy.ConclusionsThe aim of this study was to evaluate the potential contribution of magnetic resonance imaging in diagnostic procedure after inconclusive ultrasound examination during the assessment of fetal urinary tract abnormalities in the third trimester.

Early second-trimester diagnosis of body stalk anomaly by fetal magnetic resonance imaging

We report a case of body stalk anomaly detected prenatally by fetal magnetic resonance imaging (MRI) at 14 weeks' gestation. A 29-year-old woman was followed during her first pregnancy. At 11-12 weeks' gestation, our sonographic images showed multiple fetal deformities. An abdominal wall defect was suspected. The exteriorized abdominal contents and the lower limb appeared within the extraembryonic celom with an intact amniotic membrane. Fetal MRI at 14 weeks' gestation confirmed a large anterior wall defect with herniation of the liver and bowel. In addition, abnormally rotated lower limb and scoliosis could be demonstrated. The fetus was prenatally diagnosed with body stalk anomaly, expected to be lethal in nature. The parents decided to terminate the pregnancy at 15 weeks' gestation. Prenatal diagnosis of body stalk anomaly is usually based on sonographic findings. As far as we are aware, this is the first case report of body stalk anomaly satisfactorily diagnosed by fetal MRI in the early second trimester. Fetal MRI scans should provide ground for a precise antenatal diagnosis of body stalk anomaly from early gestation.

Polymicrogyria in a fetus with human parvovirus B19 infection: a case with radiologic–pathologic correlation

We report the prenatal magnetic resonance imaging (MRI) appearance of polymicrogyria with pathologic correlation in a fetus with congenital parvovirus B19 infection. Prenatal ultrasound revealed non-immune hydrops, but detected no fetal brain abnormalities. A subsequent fetal MRI scan performed at 23 weeks' gestation demonstrated bilateral polymicrogyria, which was confirmed at autopsy. To our knowledge, prenatal diagnosis of polymicrogyria in association with congenital parvovirus B19 infection has not been previously described. This case provides further evidence for brain abnormalities resulting from congenital parvovirus B19 infection, and suggests that fetal neuroimaging with MRI would be of value in suspected cases of congenital parvovirus infection.

Ovarian cysts on prenatal MRI

ObjectiveOvarian cysts are the most frequently encountered intra-abdominal masses in females in utero. They may, at times, require perinatal intervention. Using magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US) in prenatal diagnosis, we sought to demonstrate the ability to visualize ovarian cysts on prenatal MRI. Materials and methodsThis retrospective study included 17 fetal MRI scans from 16 female fetuses (23–37 gestational weeks) with an MRI diagnosis of ovarian cysts after suspicious US findings. A multiplanar MRI protocol was applied to image and to characterize the cysts. The US and MRI findings were compared, and the prenatal findings were compared with postnatal imaging findings or histopathology. ResultsSimple ovarian cysts were found in 10/16 cases and complex cysts in 7/16 cases, including one case with both. In 11/16 (69%) cases, US and MRI diagnoses were in agreement, and, in 5/16 (31%) cases, MRI specified or expanded the US diagnosis. In 6/16 cases, postnatal US showed that the cysts spontaneously resolved or decreased in size, and in 1/16 cases, postnatal imaging confirmed a hemorrhagic cyst. In 4/16 cases, the prenatal diagnoses were confirmed by surgery/histopathology, and for the rest, postnatal correlation was not available. ConclusionOur results illustrate the MRI visualization of ovarian cysts in utero. In most cases, MRI will confirm the US diagnosis. In certain cases, MRI may provide further diagnostic information, additional to US, which is the standard technique for diagnosis, monitoring, and treatment planning.

Neuroanatomy of the Subadult and Fetal Brain of the Atlantic White‐sided Dolphin (Lagenorhynchus acutus) from in Situ Magnetic Resonance Images

This article provides the first anatomically labeled, magnetic resonance imaging (MRI) -based atlas of the subadult and fetal Atlantic white-sided dolphin (Lagenorhynchus acutus) brain. It differs from previous MRI-based atlases of cetaceans in that it was created from images of fresh, postmortem brains in situ rather than extracted, formalin-fixed brains. The in situ images displayed the classic hallmarks of odontocete brains: fore-shortened orbital lobes and pronounced temporal width. Olfactory structures were absent and auditory regions (e.g., temporal lobes and inferior colliculi) were enlarged. In the subadult and fetal postmortem MRI scans, the hippocampus was identifiable, despite the relatively small size of this structure in cetaceans. The white matter tracts of the fetal hindbrain and cerebellum were pronounced, but in the telencephalon, the white matter tracts were much less distinct, consistent with less myelin. The white matter tracts of the auditory pathways in the fetal brains were myelinated, as shown by the T2 hypointensity signals for the inferior colliculus, cochlear nuclei, and trapezoid bodies. This finding is consistent with hearing and auditory processing regions maturing in utero in L. acutus, as has been observed for most mammals. In situ MRI scanning of fresh, postmortem specimens can be used not only to study the evolution and developmental patterns of cetacean brains but also to investigate the impacts of natural toxins (such as domoic acid), anthropogenic chemicals (such as polychlorinated biphenyls, polybrominated diphenyl ethers, and their hydroxylated metabolites), biological agents (parasites), and noise on the central nervous system of marine mammal species.

Comparison of prenatal and postnatal MRI findings in the evaluation of intrauterine CNS anomalies requiring postnatal neurosurgical treatment

To assess the diagnostic capability of fetal magnetic resonance imaging (MRI) in children suspected antenatally to harbor central nervous system (CNS) defects that require immediate postnatal neurosurgical treatment. Between 2003 and 2005, 13 fetal MRI scans were performed in mothers suspected to have fetuses with congenital CNS defects that would require surgery soon after birth. Comparisons between antenatal and postnatal scans were made with emphasis on diagnostic accuracy of antenatal examinations. All mothers were scanned using heavily T2-weighted fat-saturated sequences, allowing rapid acquisitions to avoid movement artefacts. Imaging quality was satisfactory in all patients. Diagnoses made antenatally were: myelomeningocele in seven, meningocele in one, diastematomyelia in one, occipital meningocele in one, and isolated hydrocephalus in three children. Of the seven children with antenatal diagnosis of myelomeningocele, one proved to have spinal lipoma postnatally. The patient who antenatally was diagnosed with meningocele proved to have spinal lipoma postnatally. These two were early antenatal MR scans. Antenatal diagnosis of hydrocephalus was made in five of the six confirmed myelomeningocele patients, which was verified postnatally. Antenatal diagnosis of Chiari II malformation was made in all six confirmed myelomeningocele patients. The antenatal diagnoses of occipital meningo-encephalocele and isolated hydrocephalus were verified postnatally. Antenatal diagnosis of diastematomyelia was not verified postnatally. Fetal MRI scanning is an effective, noninvasive method of assessing in-utero CNS abnormalities. The diagnostic accuracy has improved to allow prediction of clinical outcome and counseling for possible treatment, but is not perfect yet to allow counseling for termination of pregnancy.

Fetal abdominal magnetic resonance imaging

This review deals with the in vivo magnetic resonance imaging (MRI) appearance of the human fetal abdomen. Imaging findings are correlated with current knowledge of human fetal anatomy and physiology, which are crucial to understand and interpret fetal abdominal MRI scans. Because fetal MRI covers a period of more than 20 weeks, which is characterized not only by organ growth, but also by changes and maturation of organ function, a different magnetic resonance appearance of the fetal abdomen results. This not only applies to the fetal intestines, but also to the fetal liver, spleen, and adrenal glands. Choosing the appropriate sequences, various aspects of age-related and organ-specific function can be visualized with fetal MRI because these are mirrored by changes in signal intensities. Knowledge of normal development is essential to delineate normal from pathological findings in the respective developmental stages.